Heart failure is a common disease with a prevalence of approximately 2-3 percent in the general population. The disease has a huge impact both on health economy and the well-being of people in western society. Cardiac Resynchronization Therapy (CRT) is an established method to treat heart failure in patients with low ejection fraction and widened QRS-complex. The optimal method to monitor the effects of CRT is however under debate. CRT has important effects on both systolic and diastolic cardiac function. Heart failure affects both systolic and diastolic function.
There is therefore a need for a diagnostic parameter that is descriptive of changes both in diastolic and systolic cardiac properties and which can be used, among others, as control parameter for CRT optimization.
Furthermore, the parameter should be determinable by an implantable medical device, such as pacemaker, defibrillator or cardioverter, having functionality for providing the cardiac resynchronization therapy to the heart failure patient.
A vast number of diagnostic parameters have been used in the art for optimizing CRT of an implantable medical device, such as maximum ventricular
      ⅆ    P        ⅆ    t  using a ventricular pressure sensor (1), heart sound measurements (2), a map of conduction time between multiple heart sites (3), stroke volume derived from blood pressure in the aorta (4) and left ventricular lateral wall acceleration (5).
These prior art parameters and implantable medical devices typically require dedicated sensor equipment, such as pressure sensors, acoustic sensors, acceleration sensors, resulting in more complex devices and more problematic implantation of the devices.
Furthermore, not all prior art parameters are indeed particularly suitable as CRT optimization parameters as they are not descriptive of changes both in diastolic and systolic cardiac properties.